Two-Stage Left-Turn and Bike Box (advanced stop bar)

Bike boxes increase the visibility of people biking at an intersection and improve safety for cyclists making left turns at signalized or complex intersections. A bike box (also known as “advance stop bar”) is a designated area in front of the traffic lane at a signalized intersection which provides bicyclists with a safe and visible space to get ahead of vehicle queues and clear the intersection quickly upon a green light. A two-stage left turn (TSLT) queue box provides people biking with a safer and more comfortable way to make left turns, particularly at high volume, higher speed, or multilane intersections.

A person on a bike waits in a green painted bike box at a signalized intersection. 
 A green box with a sharrow is panted across the roadway, parallel to a crosswalk, providing a space for bikes to wait at the signal ahead of queueing vehicles.
San Diego, CA (Kittelson & Associates, Inc.) Washington, D.C. (Kittelson & Associates, Inc.)

 

Program Goals This Project Type Meets

  • Increase safety (bicycle)
  • Improve travel options

Typical Applications

  • Signalized, multilane intersection with designated bike lanes (TSLT)
  • Unsignalized intersections or mid-block crossings (TSLT)
  • Roadways with high cyclist or vehicle volumes/speeds
  • Along cycle tracks
  • Where bicycle facilities cross streetcar tracks
  • On corridors with frequent vehicular right turning movements or bicycle left turns
  • Where dominant vehicle traffic flows right and bicycle traffic continues through (e.g., Y intersection or access ramp) (Bike Box)

Material Options

Design Considerations

  • Use solid green paint or durable pavement to increase visibility
  • Pavement markings should include bicycle stencil and turn arrow to indicate bicycle turning direction
  • TSLT box should be located in a protected area e.g., one or all of the above:
    • Outside the path of through vehicle traffic
    • Between the bicycle lane and pedestrian crossing
    • Within on-street parking lane
  • In constrained locations, a bike box may double as a TSLT box
  • A bike box is typically 10-16 ft deep
  • Requires formal request and approval from FHWA to use under current interim approval

Other Considerations

  • Consider using a TSLT box to help cyclists transition between one way and two-way bike facilities or other complex movements (such as midblock crossings from the right lane)
  • Install “Stop Here on Red” (R10-6) signs to denote location of relocated stop bar
  • Install “No Turn on Red” (R10-11) signs and “Except Bicycles” plaques to prevent vehicles from encroaching on the bike box area
  • Provide bicycle crossing markings through intersection to define bicycle path to the box
  • Bicycle signals with a leading interval may be installed in conjunction with TSLT box
  • Green pavement markings may require more frequent maintenance or reapplication
  • Two stage turns may increase comfort as well as delay as the cyclist needs two green cycles (one for the through street and one for the cross street) to complete the turn
  • Does not benefit cyclists approaching intersection on a green signal

Other Resources

Related Information

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